Electric switch



W. E. LEIBING ELECTRIC SWITCH Sept. 4, 1951 Filed Feb. 21. 1949 6, w W MT a m Em W my w M M Patented Sept. 4, 1951 UNITED STATES PATENT OFFICEELECTRIC SWITCH William E. Leibing, Los Angeles, Calif. ApplicationFebruary 21, 1949, Serial No. 77,526

3 Claims.

This invention relates to electric switching apparatus and isparticularly directed to improvements in switch construction utilizingseparable contacts positioned in a chemically inert medium.

Electrical make and break switches which are required to carry anyconsiderable amount of current are commonly subject to deterioration ofthe contact points, particularly when the points are open to theatmosphere. The rapid deterioration of contact points due to arcing insuch switches has led to the use of relays operating in conjunction withthe switches to make and break the required current flow. For example,automobile horns are now commonly actuated through a relay which is inturn energized from a manually operable switch carrying very lowcurrent.

It is the principal object of this invention to provide an electricalswitch capable of carrying relatively high current without being subjectto destruction of contacts through arcing. The added expense ofsupplying and installing a relay in conjunction with the manual switchis thereby eliminated.

Another object is to provide an electrical switch having contactspositioned within an inert medium so that oxidation of the contactpoints under arcing conditions is eliminated.

Another object is to provide a switch of this type in which an inner gassurrounds the contact points and acts on a flexible impervious diaphragmfor resiliently maintaining the contacts in spaced position.

Other and more detailed objects will appear hereinafter.

In the drawings:

Figure 1 is a sectional elevation partly broken away showing a preferredembodiment of my invention and illustrating the switch contacts inspaced position.

Figure 2 is a view similar to Figure 1 showing the switch contacts inclosed position.

Referring to the drawings, a two-part housing generally designated lincludes a metallic shell II and an electrically nonconducting cover I2.The cover l2 may be formed of any suitable electrically nonconductingmaterial. The two parts of the housing I0 are maintained in assembledrelationship by means of a clamping ring I3 which encircles adjacentflanges I4 and I5 formed on the shell II and cover I2 respectively.

A flexible impervious diaphragm I6 is positioned within the housing I0.This diaphragm I6 is clamped on its outer rim between the flanges I4 andI5 and is thus held securely in place. The clamping ring I3 confines theouter rim of the diaphragm I6 under compression between the flanges I4and I5.

The cover I2 may be provided with a central axially extending opening I8which acts as a guide for the metallic plunger I9 extending through theopening into the interior of the housing I0. The plunger I9 is providedwith an integral enlarged head 20 adapted to engage the central portionof the diaphragm IS. A metallic button or cap 2| is provided with acentral projection 22 which extends into an axial recess 23 provided inthe plunger I9. The projection 22 also extends through a central opening24 provided in the diaphragm I6. The projection 22 is press-fitted intothe recess 23 so that the central portion of the diaphragm I6 is clampedunder compression between the head 20 and th button or cap 2|.

An inert gas such as, for example, nitrogen or argon, is admitted intothe chamber I1 defined by the shell II and diaphragm I6. The gas isadmitted through passage 25 which is subsequently closed by any suitablemeans such as, for example, by the lead plug 26. Pressure of the inertgas within the chamber II opposes atmospheric pressure within the coverI2 and normally maintains the plunger I9 in the position shown inFigure 1. On or more ports 21 may be formed in the cover I2 to admitatmospheric pressure into the interior of the cover I2.

Manual pressure exerted against the end 28 of the plunger l9 compressesthe gas within the chamber I'I sufiiciently to bring the contact faces29 and 30 into engagement. These faces are formed as part of themetallic elements 2| and I I. An electrical lead Wire 3I may beelectrically connected in any suitable way to the contact element 2|,and as shown in the drawings this electrical connection may take theform of an attaching screw 32 connecting the lead wire 3| with thmetallic plunger I9. The electrical connection is then establishedthrough the metallic projection 22 to the movable switch contact 2|. Theshell II may be connected electrically to the other lead which may takethe form of a metallic bracket 33 grounded by means of an attachmentbolt 34 connected to a supporting frame (not shown). The bracket 33 maybe provided with an aperture 35 through which the threaded boss 36extends. This boss 36 may be formed integrally with the shell Ii.A-clamping nut 31 serves to hold the bracket 33 in assembledrelationship with respect to the housing I0. 7

An electrical connection is closed between the lead wire 3| and theground ng belt it when the plunger 19 is manually mote-ii to bring thecon tact surfac s 29 and 30 into engagement. When manual pressure isreleased from the end surface 28 the pressure of the inert gas withinthe chamber I! flexes the diaphragm IE to return the plunger to the openposition shown in Figure 1 and thereby separate the contact faces 29 and30. Although arcing may occur when the contact surfaces are separated,no serious destructive efi'ects occur because oxygen is excluded fromthe chamber I! and hence oxidation cannot occur with arcing. Thepressure of the inert gas is above atmospheric pressure so that theswitch is normally open.

It is essential that the diaphragm l6 be substantially impervious sothat the inert gas does not leak through the diaphragm out of thechamber I1. I have found that commercially available synthetic materialsmade by Du Pont de Nemours Company under the name Fairprene" 5002 or5003, or Chicago Rawhide Company under the name of Servene" 8083 givessatisfactory results.

It will be understood from this description that the inert gas servestwo purposes. It excludes oxygen from the contact points so that arcingis not objectionable and it acts against the diaphragm normally tomaintain the switch contacts in open position.

In this specification and in the claims I have used the word inert" inconnection with gases to designate gases which protect electricalcontact points from excessive damage or decay under arcing conditions,and therefor inert gases as thus defined are not necessarily fully inertin the chemical sense.

The use of gas under compression to resiliently maintain the contactpoints in spaced relationship eliminates the requirement of a metallicspring, and hence the switch construction embodying my invention may beeconomically constructed in quantity and on a competitive basis to makeand break switches which must be used in conjunction with relays toavoid pitting of contacts.

. My improved switch construction is particularly well suited for use inmines, powder maga-, zines, refineries and other locations where it isessential that make and break electric switches be protected so thatarcing of contacts cannot cause an explosion. Since the contacts of myimproved switch construction are mounted in an enclosed chamber, thereis no possibility that arcing across the switch points might set fire toan explosive mixture in the atmosphere.

While in the drawings I have shown the construction which provides astop for movement of the plunger in one direction only, it will berecognized that a stop for limiting the movement of the plunger in theother direction can be had if necessary or desirable. Such a stop couldbe conveniently mounted on the cover l2 and arthe details herein setforth, but my invention is of the full scope of the appended claims.

I claim:

1. In an electric switch construction, the comhination or a shell, aflexible diaphragm cooperating with the shell to form an enclosedchamber,-a stationary contact element on the shell, a movable contactelement on th diaphragm, said contact elements being within saidchamber, the chamber being filled with an inert gas under pressure, thepressure of the gas acting to move the diaphragm in a direction to holdthe contact elements in spaced relationship, and manually operable meansaccessible exteriorly of the shell whereby the diaphragm may be movedagainst the pressure of the gas to engag the electrical contactelements.

2. In an electric switch construction, the combination of anelectrically conducting shell, an electrically nonconducting cover fixedrelative to the shell, a flexible diaphragm clamped between the coverand shell and cooperating with the shell to define an enclosed chamber,a stationary contact element on the shell, a movable contact elementsecured relative to the diaphragm, said contact elements beingpositioned within said chamber, an electrically conducting plunger fixedrelative t the movable contact element and extending exteriorly of saidcover, the chamber being filled with an inert gas under pressure, thepressure of the gas acting on the diaphragm to move the movable contactelement away from the stationary contact element, the plunger beingmovably manually against the pressure of the gas to brin said elementsinto contact.

3. In an electric switch construction, the combination of anelectrically conducting shell, an electrically nonconducting cover fixedrelative to the shell and provided with a central opening, a flexiblediaphragm, cooperating flanges on the cover and shell clamping the outerportion of the diaphragm therebetween, the diaphragm cooperating withthe shell to define an enclosed chamber therebetween, a stationarycontact element on the shell, a movable contact element secured'to thecentral portion of the diaphragm, said contact elements being positionedwithin said chamber, a plunger guided for axial movement within thecentral opening in the cover, the chamber being filled with an inert gasunder pressure, the pressure of the gas acting on the diaphragm to movethe movable contact element away from the stationary contact element,the plunger being movable manually against the pressure of the gas tobring said elements into engagement.

WILLIAM E. LEIBING.

REFERENCES CITED UNITED STATES PATENTS

